Preemptive Kernel Research Articles

Behaviour and performance comparison between FreeRTOS and µC/OS-III

As the prevalence of embedded systems in various fields has spread, real-time operating systems (RTOSs) have been widely used for many years satisfying real-time requirements and a multitasking design. The use of RTOS adds additional overhead to a system, which should be deliberately considered and evaluated in some critical systems. This paper presents a qualitative and quantitative comparison between an open-source RTOS (FreeRTOS V8.0.0) and a commercial one (?C/OS-III). Both RTOS use a preemptive multitasking kernel, with additional support for round robin scheduling. We aim to benchmark and evaluate their performance and behaviour, including seven performance tests and two behaviour tests. Comparing the measurement results shows that the commercial µC/OS-III does not behave much better than FreeRTOS. Furthermore, we discovered that the priority changing function of µC/OSIII does not behave correctly in some circumstances. Although FreeRTOS has no such problem in the latest version, it still has a problem with its dynamic memory management.

Design of Networked Home Automation System Based on μCOS-II and AMAZON

In recent years, with the popularity of computers and smart phones and the development of intel- ligent building in electronics industry, people's requirement of living environment is gradually changing. The intelligent home furnishing building has become the new focus of people purchasing. And the networked home automation system which relies on the advanced network technology to connect with air conditioning, lighting, security, curtains, TV, water heater and other home furnishing systems into a local area network becomes a net- worked control system. μC /OS is a real-time operating system with the free open-source code, the compact structure and the preemptive real-time kernel. In this paper, the author focuses on the design of home furnishing total controller based on AMAZON multimedia processor and μC/OS-II real-time operating system, and achieves the remote access connection and control through the Ethernet.

Research on A.C. Sampling Technique for the Electric Parameters Based on Embedded Linux and Frequency Self-Adapting

Directed at the traditional single chip microcomputer system which didn’t have the managing ability of the modern operating system, a technology of AC synchronization sampling was presented and implements which were based on embedded microprocessor S3C2410 and Linux real-time operating system kernel. The technology divided the sampling process into 2-part, frequency dynamic tracking and same-internal synchronization sampling .The multi-tasks, which process the different priorities, used to actualize sampling the signal and treating with the data. All tasks were scheduled by the preemptive Linux kernel. The technology has decreased the conflict between the precision and real-time property. The construction of hardware and software, method of constituting real-time operating system based on Linux kernel, signal frequency measuring, signal sampling and harmonic computing were introduced in detail.

Modular verification of preemptive OS kernels

AbstractMost major OS kernels today run on multiprocessor systems and are preemptive: it is possible for a process running in the kernel mode to get descheduled. Existing modular techniques for verifying concurrent code are not directly applicable in this setting: they rely on scheduling being implemented correctly, and in a preemptive kernel, the correctness of the scheduler is interdependent with the correctness of the code it schedules. This interdependency is even stronger in mainstream kernels, such as those of Linux, FreeBSD or Mac OS X, where the scheduler and processes interact in complex ways. We propose the first logic that is able to decompose the verification of preemptive multiprocessor kernel code into verifying the scheduler and the rest of the kernel separately, even in the presence of complex interdependencies between the two components. The logic hides the manipulation of control by the scheduler when reasoning about preemptable code and soundly inherits proof rules from concurrent separation logic to verify it thread-modularly. We illustrate the power of our logic by verifying an example scheduler, which includes some of the key features of the scheduler from Linux 2.6.11 challenging for verification.

Modular verification of preemptive OS kernels

Most major OS kernels today run on multiprocessor systems and are preemptive: it is possible for a process running in the kernel mode to get descheduled. Existing modular techniques for verifying concurrent code are not directly applicable in this setting: they rely on scheduling being implemented correctly, and in a preemptive kernel, the correctness of the scheduler is interdependent with the correctness of the code it schedules. This interdependency is even stronger in mainstream kernels, such as Linux, FreeBSD or XNU, where the scheduler and processes interact in complex ways. We propose the first logic that is able to decompose the verification of preemptive multiprocessor kernel code into verifying the scheduler and the rest of the kernel separately, even in the presence of complex interdependencies between the two components. The logic hides the manipulation of control by the scheduler when reasoning about preemptable code and soundly inherits proof rules from concurrent separation logic to verify it thread-modularly. This is achieved by establishing a novel form of refinement between an operational semantics of the real machine and an axiomatic semantics of OS processes, where the latter assumes an abstract machine with each process executing on a separate virtual CPU. The refinement is local in the sense that the logic focuses only on the relevant state of the kernel while verifying the scheduler. We illustrate the power of our logic by verifying an example scheduler, modelled on the one from Linux 2.6.11.

A Software Architecture for Adaptive Modular Sensing Systems

By combining a number of simple transducer modules, an arbitrarily complex sensing system may be produced to accommodate a wide range of applications. This work outlines a novel software architecture and knowledge representation scheme that has been developed to support this type of flexible and reconfigurable modular sensing system. Template algorithms are used to embed intelligence within each module. As modules are added or removed, the composite sensor is able to automatically determine its overall geometry and assume an appropriate collective identity. A virtual machine-based middleware layer runs on top of a real-time operating system with a pre-emptive kernel, enabling platform-independent template algorithms to be written once and run on any module, irrespective of its underlying hardware architecture. Applications that may benefit from easily reconfigurable modular sensing systems include flexible inspection, mobile robotics, surveillance, and space exploration.

A portable real-time kernel for 8086/80186/80286/80386 based systems on IBM-PC

The design of a portable real-time kernel is discussed. This kernel provides an environment where a portable real-time software can be developed for 8086/80186/80286/80386 based target systems. The kernel is hosted on IBM compatible PCs of the XT/AT class. The programmer can always utilize the existing debugging tools on PC to correct the bugs and immediately evaluate the software with the kernel. This is a possible alternative to the use expensive, processor specific hardware emulators. The use of an inexpensive PC running a multi-process, pre-emptive kernel can be regarded as a new concept for real-time software developement, effectively replacing a universal development system with hardware emulation capacity. Besides the above facility DOS interface is also available with the kernel. The user can use the DOS functions at any time with some protocol in the case of a PC being used with the real_time system as monitor or control equipment. Over the kernel there is a window manager layer. Using this, the user can create windows for each process to display any output.